<?php
class GIFEncoder
{
	
	var $GIF = "GIF89a"; /*
	                      * GIF header 6 bytes
	                      */
	
	var $VER = "GIFEncoder V2.05"; /*
	                                * Encoder version
	                                */
	
	var $BUF = Array();
	
	var $LOP = 0;
	
	var $DIS = 2;
	
	var $COL = - 1;
	
	var $IMG = - 1;
	
	var $ERR = Array(
			
			ERR00 => "Does not supported function for only one image!",
			
			ERR01 => "Source is not a GIF image!",
			
			ERR02 => "Unintelligible flag ",
			
			ERR03 => "Does not make animation from animated GIF source"
	);
	
	/**
	 *
	 * @param $GIF_src 静态gif文件路径数组       	
	 *
	 * @param $GIF_dly 每个静态gif文件的显示时间数组，单位百分之一秒       	
	 *
	 * @param $GIF_lop 循环次数，0表示无限循环
	 *       	 0: “No disposal method”：不做任何处理直接显示下一帧；
	 *       	
	 *       	 1: “Leave alone”：和上面一项效果相同，也是不做任何处理直接显示下一帧；
	 *       	
	 *       	 2: “Background color”：在显示下一帧前先用背景色填充画面；
	 *       	
	 *       	 3: “Restore previous”：在显示下一帧前先把画面恢复为显示当前帧的上一帧；
	 *       	
	 * @param
	 *       	 $GIF_dis
	 *       	
	 * @param $GIF_red 指定静态gif文件上面的透明色，如不指定则，统一为-1       	
	 *
	 * @param $GIF_mod 一般采用url，指$GIF_src指向了静态gif文件       	
	 *
	 *
	 */
	
	function GIFEncoder($GIF_src, $GIF_dly, $GIF_lop, $GIF_dis, $GIF_red, $GIF_grn, $GIF_blu, $GIF_mod)
	{
		
		if (! is_array($GIF_src) && ! is_array($GIF_dly))
		{
			
			printf("%s: %s", $this->VER, $this->ERR['ERR00']);
			
			exit(0);
		
		}
		
		$this->LOP = ($GIF_lop > - 1) ? $GIF_lop : 0;
		
		$this->DIS = ($GIF_dis > - 1) ? (($GIF_dis < 3) ? $GIF_dis : 3) : 2;
		
		$this->COL = ($GIF_red > - 1 && $GIF_grn > - 1 && $GIF_blu > - 1) ? 

		($GIF_red | ($GIF_grn << 8) | ($GIF_blu << 16)) : - 1;
		
		for($i = 0; $i < count($GIF_src); $i ++)
		{
			
			if (strToLower($GIF_mod) == "url")
			{
				
				$this->BUF[] = fread(fopen($GIF_src[$i], "rb"), filesize($GIF_src[$i]));
			
			} 

			else if (strToLower($GIF_mod) == "bin")
			{
				
				$this->BUF[] = $GIF_src[$i];
			
			} 

			else
			{
				
				printf("%s: %s ( %s )!", $this->VER, $this->ERR['ERR02'], $GIF_mod);
				
				exit(0);
			
			}
			
			if (substr($this->BUF[$i], 0, 6) != "GIF87a" && substr($this->BUF[$i], 0, 6) != "GIF89a")
			{
				
				printf("%s: %d %s", $this->VER, $i, $this->ERR['ERR01']);
				
				exit(0);
			
			}
			
			for($j = (13 + 3 * (2 << (ord($this->BUF[$i]{10}) & 0x07))), $k = TRUE; $k; $j ++)
			{
				
				switch ($this->BUF[$i]{$j})
				{
					
					case "!" :
						
						if ((substr($this->BUF[$i], ($j + 3), 8)) == "NETSCAPE")
						{
							
							printf("%s: %s ( %s source )!", $this->VER, $this->ERR['ERR03'], ($i + 1));
							
							exit(0);
						
						}
						
						break;
					
					case ";" :
						
						$k = FALSE;
						
						break;
				
				}
			
			}
		
		}
		
		GIFEncoder::GIFAddHeader();
		
		for($i = 0; $i < count($this->BUF); $i ++)
		{
			
			GIFEncoder::GIFAddFrames($i, $GIF_dly[$i]);
		
		}
		
		GIFEncoder::GIFAddFooter();
	
	}
	
	function GIFAddHeader()
	{
		
		$cmap = 0;
		
		if (ord($this->BUF[0]{10}) & 0x80)
		{
			
			$cmap = 3 * (2 << (ord($this->BUF[0]{10}) & 0x07));
			
			$this->GIF .= substr($this->BUF[0], 6, 7);
			
			$this->GIF .= substr($this->BUF[0], 13, $cmap);
			
			$this->GIF .= "!\377\13NETSCAPE2.0\3\1" . GIFEncoder::GIFWord($this->LOP) . "\0";
		
		}
	
	}
	
	function GIFAddFrames($i, $d)
	{
		
		$Locals_str = 13 + 3 * (2 << (ord($this->BUF[$i]{10}) & 0x07));
		
		$Locals_end = strlen($this->BUF[$i]) - $Locals_str - 1;
		
		$Locals_tmp = substr($this->BUF[$i], $Locals_str, $Locals_end);
		
		$Global_len = 2 << (ord($this->BUF[0]{10}) & 0x07);
		
		$Locals_len = 2 << (ord($this->BUF[$i]{10}) & 0x07);
		
		$Global_rgb = substr($this->BUF[0], 13, 

		3 * (2 << (ord($this->BUF[0]{10}) & 0x07)));
		
		$Locals_rgb = substr($this->BUF[$i], 13, 

		3 * (2 << (ord($this->BUF[$i]{10}) & 0x07)));
		
		$Locals_ext = "!\xF9\x04" . chr(($this->DIS << 2) + 0) . 

		chr(($d >> 0) & 0xFF) . chr(($d >> 8) & 0xFF) . "\x0\x0";
		
		if ($this->COL > - 1 && ord($this->BUF[$i]{10}) & 0x80)
		{
			
			for($j = 0; $j < (2 << (ord($this->BUF[$i]{10}) & 0x07)); $j ++)
			{
				
				if (

				ord($Locals_rgb{3 * $j + 0}) == (($this->COL >> 16) & 0xFF) && 

				ord($Locals_rgb{3 * $j + 1}) == (($this->COL >> 8) & 0xFF) && 

				ord($Locals_rgb{3 * $j + 2}) == (($this->COL >> 0) & 0xFF))
				
				{
					
					$Locals_ext = "!\xF9\x04" . chr(($this->DIS << 2) + 1) . 

					chr(($d >> 0) & 0xFF) . chr(($d >> 8) & 0xFF) . chr($j) . "\x0";
					
					break;
				
				}
			
			}
		
		}
		
		switch ($Locals_tmp{0})
		{
			
			case "!" :
				
				$Locals_img = substr($Locals_tmp, 8, 10);
				
				$Locals_tmp = substr($Locals_tmp, 18, strlen($Locals_tmp) - 18);
				
				break;
			
			case "," :
				
				$Locals_img = substr($Locals_tmp, 0, 10);
				
				$Locals_tmp = substr($Locals_tmp, 10, strlen($Locals_tmp) - 10);
				
				break;
		
		}
		
		if (ord($this->BUF[$i]{10}) & 0x80 && $this->IMG > - 1)
		{
			
			if ($Global_len == $Locals_len)
			{
				
				if (GIFEncoder::GIFBlockCompare($Global_rgb, $Locals_rgb, $Global_len))
				{
					
					$this->GIF .= ($Locals_ext . $Locals_img . $Locals_tmp);
				
				} 

				else
				{
					
					$byte = ord($Locals_img{9});
					
					$byte |= 0x80;
					
					$byte &= 0xF8;
					
					$byte |= (ord($this->BUF[0]{10}) & 0x07);
					
					$Locals_img{9} = chr($byte);
					
					$this->GIF .= ($Locals_ext . $Locals_img . $Locals_rgb . $Locals_tmp);
				
				}
			
			} 

			else
			{
				
				$byte = ord($Locals_img{9});
				
				$byte |= 0x80;
				
				$byte &= 0xF8;
				
				$byte |= (ord($this->BUF[$i]{10}) & 0x07);
				
				$Locals_img{9} = chr($byte);
				
				$this->GIF .= ($Locals_ext . $Locals_img . $Locals_rgb . $Locals_tmp);
			
			}
		
		} 

		else
		{
			
			$this->GIF .= ($Locals_ext . $Locals_img . $Locals_tmp);
		
		}
		
		$this->IMG = 1;
	
	}
	
	function GIFAddFooter()
	{
		
		$this->GIF .= ";";
	
	}
	
	function GIFBlockCompare($GlobalBlock, $LocalBlock, $Len)
	{
		
		for($i = 0; $i < $Len; $i ++)
		{
			
			if (

			$GlobalBlock{3 * $i + 0} != $LocalBlock{3 * $i + 0} || 

			$GlobalBlock{3 * $i + 1} != $LocalBlock{3 * $i + 1} || 

			$GlobalBlock{3 * $i + 2} != $LocalBlock{3 * $i + 2})
			
			{
				
				return (0);
			
			}
		
		}
		
		return (1);
	
	}
	
	function GIFWord($int)
	{
		
		return (chr($int & 0xFF) . chr(($int >> 8) & 0xFF));
	
	}
	
	function GetAnimation()
	{
		
		return ($this->GIF);
	
	}

}

?>